This specification relates generally to user authentication and, in particular, to identity and phone number verification.
Two-factor authentication is a method for authenticating a user's identity by combining two different factors associated with the user. Each factor can be an object that the user possesses (e.g., a bank card, a mobile phone, a key, a driver's license), information the user knows (e.g., a password, a birth date, a Personal Identification Number or PIN number), or a characteristic of the user (e.g., one or more fingerprints, a signature, facial look). The user's identity can be authenticated when both factors are verified. Two-factor authentication is generally more secure than single factor authentication.